In a networked computer environment, multiple copies of data are often passed around from system to system. In many cases, the copies become stale due to being out of date, no longer needed, or because they expose data that is a security risk. In these situations, it is desirable to delete the stale copies. However, tracking and deleting the stale copies is difficult or impossible. There may be no mechanism for determining which systems received the data, and the destination system may not have installed an application or service to detect and delete stale data.
The primary mechanism currently in use to handle this problem is to limit the copying of data to prevent it from becoming stale. When the data is only stored in one central location (e.g. a single database, a single file on a particular machine's hard drive) access control, deletions, and updates can be performed by a single application. In other cases, it may be the responsibility of the user to locate and delete stale data.
It is often useful or necessary to create copies of data. A central database or filesystem may be inadequate for several reasons, such as scalability concerns, user convenience, or application responsiveness. Relying on users to locate and delete stale data is error prone. Consequently, what is needed is a mechanism to locate and delete stale data regardless of where it has been copied.